Kate Becker: Quantum physics has been rankling scientists for decades

Seriously. The deep questions raised by quantum theory have so troubled so many thinkers for so long that a trio of physicists decided to settle things Gallup style.

At a conference called "Quantum Physics and the Nature of Reality," held in July 2011, they offered up a survey: In 16 questions, they asked their colleagues -- a group of physicists, mathematicians and philosophers -- to report their feelings on the very foundations of physics. If this seems ambitious, don't fret: It was multiple choice.

Through the poll, they hoped to take the pulse of the physics community on questions like these: Does randomness lie at the heart of physics? Do we really change the universe just by looking at it? Can objects really be in two, three or an infinite number of locations at once?

Physicists have debated these questions ever since they got their first glimpse at the topsy-turvy world of quantum theory. The equations of quantum mechanics are elegant and practical -- they look good and they work -- but their deeper implications are so counterintuitive that they have divided the physics community for decades.

For instance, consider a quantum quandary like this: You've found yourself a particle -- say, an electron -- and you want to measure a particular property called spin. (Though electrons aren't actually spinning, spin sums up the properties, like angular momentum, that they would have if they were spinning.)

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There are two possible outcomes: Either it's spinning "up," or it's spinning "down." So you take your measurement, and voila! Spin up! But quantum mechanics won't tell you what the electron was doing immediately before you took that measurement. In fact, mathematically, it seems that the electron was spinning both ways at once until your measurement forced it to make a choice.

Does that mean that the entire universe exists in some sort of limbo? That, until we come along and start poking and prodding at it, there is no definitive reality at all?

This most literal take on quantum physics, often called the Copenhagen interpretation, is what you're most likely to encounter in a physics classroom. Yet it has rankled physicists as eminent as Albert Einstein. To these thinkers, the Copenhagen interpretation amounts to an argument that the world ceases to exist the moment you close your eyes, or that page 100 of the novel on your nightstand remains blank until the moment you turn over page 99. In other words: It just doesn't smell right.

So how did it fare in the poll? It came out on top, with 42 percent of the votes. The information interpretation, which suggests that information, not matter or energy, is the fundamental "stuff" of the universe, came in a distant second, with 24 percent. Close behind in third, at 18 percent, was that sci-fi favorite, the many-worlds interpretation, according to which every quantum measurement actually splits the universe into multiple, parallel universes.

"Other" and "no preferred interpretation" tied for fourth place, with 12 percent apiece. (Yes, eagle-eyed readers, something fishy is going on with the math here: Respondents were allowed to vote for more than one choice.)

You might say, then, that the Copenhagen interpretation is on the decline. Though Copenhagen has been around since the 1920s, the many-worlds idea didn't arise until the 1950s, and quantum information theory is an even later entry into the race, suggesting that physicists are hungry for new ways of thinking about quantum mechanics.

Yet I think the most telling question on the poll is Question 13: How often have you switched to a different interpretation?

Forty-two percent of the scientists polled said they'd changed their minds at least once. And though a third claimed never to have changed their interpretation, ever, one respondent wrote in that he "sometimes switches interpretation several times per day" -- a response that seems both candid and very much in the spirit of quantum physics itself.

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